Imparting a color change or color effect on hair can be done using permanent, semi-permanent or temporary hair coloring products. A permanent hair dye can produce a substantial change in the natural color and often uses oxidative dyes that penetrate into the hair fibers to permanently change the color of the hair. Permanent hair dyes can usually last up to 4 to 5 weeks. Permanent hair coloration can also include bleaching or lightening of the hair. On the other hand, a semi-permanent hair dye, which is also referred to as hair coating or hair glazing, may provide color for about six to twelve shampoos. This type of hair dye is gentler than a permanent dye because it does not contain peroxide. These products are in contrast to temporary hair coloring products which can either give a slight change to enhance the natural color of the hair or impart bold colors or “special effects” (such as green, blue, red and pink) to human hair. These types of hair dyes make use of dye molecules that are large enough so that they do not diffuse into the hair shaft, and therefore act on the exterior of the hair. Consequently, temporary hair dyes generally wash out after one or two shampoos. The advantages of using temporary hair dyes is that they are gentle on the hair and it gives the user the flexibility to change one's hair color as desired more frequently.
Polymeric, copolymeric and oligomeric triarylmethane (TAM) dyes are known for use in the coloring of textiles, plastics, and cellulose substrates. U.S. Pat. Nos. 5,750,742, 4,477,635, and 4,353,833, the entire content of which are hereby incorporated by reference, describe the use of this class of dye, which has an improved fastness towards light and may change in hue due to prolonged exposure. However, these references do not mention the use of these dyes in a cosmetics application. US2006/0021161 A1, the entire content of which is hereby incorporated by reference, describes the use of monomeric triarylmethane dyes for temporarily coloring the hair. This reference, however, does not discuss the use of oligomeric and/or polymeric and/or copolymeric triarylmethane dyes nor does it mention the use of a flash of light to impart a color change to keratinous substrates.
While numerous temporary hair dyes currently on the market are effective in imparting a range of colors to the hair, they are not designed to impart a change in color and enhanced shine as a result of exposure to a flash of light.